Edward R Gonzales

Evaluation of flow scintillation analysis for the determination of Sr-90 in bioassay samples

An automated procedure for the determination of (90)Sr was adapted from existing methods of flow scintillation analysis (FSA) for use on aqueous samples with low levels of activity (<1000 dpm per sample). This technique employs high-performance extraction chromatography (HPEC) and an on-line liquid scintillation counter to provide automated separation and subsequent detection of (90)Sr. The total analysis time is 30 min per sample. Dilute urine samples, spiked with (90)Sr, were also processed by this method to test the application of this technique for bioassay monitoring.

Developing and evaluating di(2-ethylhexyl) orthophosphoric acid (HDEHP) based polymer ligand film (PLF) for plutonium extraction

A method was developed to produce a thin Polymer Ligand Film (PLF) using di(2-ethylhexyl) orthophosphoric acid (HDEHP) ligand for rapid extraction of plutonium. Ligands were incorporated into a polystyrene matrix to generate a smooth and durable surface for analyte extraction. PLFs were prepared with varying amount of ligands to find the optimimum ratio between the ligands and polymer structure to give best plutonium recovery. Also, the plutonium extraction is dependent on the concentration of nitric solution. This dependency was examined in the manuscript. The PLF samples were counted directly using alpha spectroscopy without any further chemical process to test the plutonium recovery. The alpha spectroscopy data shows that HDEHP based PLFs were effective in extracting plutonium from nitric acid solution. The surface characterization was performed with a scanning electron microscope (SEM) and digital autoradiography for defect examination of the PLF and plutonium distribution study, respectively.

Evaluating bis(2-ethylhexyl) methanediphosphonic acid (H2DEH[MDP]) based polymer ligand film (PLF) for plutonium and uranium extraction

This paper describes a new analyte extraction medium called polymer ligand film (PLF) that was developed to rapidly extract radionuclides. PLF is a polymer medium with ligands incorporated in its matrix that selectively and quickly extracts analytes. The main focus of the new technique is to shorten and simplify the procedure for chemically isolating radionuclides for determination through alpha spectroscopy. The PLF system was effective for plutonium and uranium extraction. The PLF was capable of co-extracting or selectively extracting plutonium over uranium depending on the PLF composition. The PLF and electrodeposited samples had similar alpha spectra resolutions.

Evaluating ligands for use in polymer ligand film (PLF) for plutonium and uranium extraction

Abstract This paper describes a new analyte extraction technique using polymer ligand film (PLF). PLFs were synthesized to perform direct sorption of analytes onto its surface for direct counting using alpha spectroscopy. The main focus of the new technique is to shorten and simplify the procedure for chemically isolating radionuclides for determination through a radiometric technique. 4′(5′)-di-t-butylcyclohexano 18-crown-6 (DtBuCH18C6) and 2-ethylhexylphosphonic acid (HEH[EHP]) were examined for plutonium extraction. Di(2-ethyl hexyl) phosphoric acid (HDEHP) were examined for plutonium and uranium extraction. DtBuCH18C6 and HEH[EHP] were not effective in plutonium extraction. HDEHP PLFs were effective for plutonium but not for uranium.